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<br />Califor..ia Regional Water Quality C,..,trol Board <br />Central Valley Region <br />Karl E. Longley, ScD, PI., Chair <br /> <br />Arnold <br />Schwarzenegger <br />Governor <br />inda S. Adams <br />.recrelory for <br />171'11'017117e Intel <br />PrOleCI 1011 <br />Sacramento Main Office <br />I 1020 Sun Center Drive 6200. Rancho Cordova. California 95670-6114 <br />Phone (916) 464-3291 • FAX 1916)464-4645 <br />hup -/Avvox.waterhoards.ca .govicentralvalley <br />30 April 2008 <br />Ms. Donna Sartini-Gardner Mr. Ronald Jr. and Ms. Bonnie Barber <br />1206 W. Struck Ave. 10411 Small Rd. <br />Orange, CA 92867 <br /> <br />Manteca, CA 95336 <br />DOCUMENT REVIEW DONNA GARDNER PROPERTY, 26090 (AKA 26056) N THORNTON ROAD <br />THORNTON SAN JOAQUIN COUNTY (REGIONAL BOARD CASE # 390412) <br />! reviewed the Soil Vapor Extraction/In-Situ Air Sparging Pilot Study Work Plan (Workplan), submitted <br />3 March 2008 by Mr, & Ms. Barber's consultant, Advanced GeoEnvironmental Inc. (AGE). The <br />Workplan proposes installation of three soil vapor extraction (SVE) wells (VW-1 through VW-3) <br />screened from 10 feet to 13 feet below ground surface (bgs) and one air sparge (AS) well (AS-1) <br />screened from 20 feet to 25 feet bgs, to be installed at the former USTs location (VW-3), near <br />monitoring well MW-4 (VW-1), and north of AS-1 (VW-2) (enclosed Figure 2, updated 29 April 2008 <br />and Figure 3 cross section). One additional monitoring well MW-7 (enclosed Figure 7) screened from <br />14 to 25 ft bgs and located approximately 20 feet south of the municipal supply well, was added on <br />29 April 2008, to provide a monitoring point between MW-4 and the municipal supply well. MW-4, <br />which is screened from 10 feet to 30 feet bgs, is located approximately 50 feet south of Thornton <br />Municipal Supply Well No 2 (Muni Well 2). Muni Well 2 has a filter pack from 70 feet bgs down to total <br />depth. In October 2007, groundwater sample results for MW-4 (enclosed Table 4 and Figure 4) were <br />Total Petroleum Hydrocarbons as gasoline, 5,300 micrograms per Liter or ug/L; toluene, 8.1 ug/L: <br />ethylbenzene. 41 ug/L, and xylenes, 73 ug/L. MW-4 sample results showed an increasing <br />concentration trend through 2007. Petroleum hydrocarbons were not detected in quarterly monitoring <br />of the remaining monitoring well samples, or in Muni Well 2. <br />The Workplan proposes an initial 8-hour SVE pilot test on the first day, with individual SVE well vapor <br />sampling (using Tedlar bags) and Organic Vapor Meter readings taken at startup and at two hour <br />intervals, with air flow rates (SVE wells) and vacuum (select monitoring wells by meter) also recorded <br />at 30-minute intervals. A 72-hour SVE/AS pilot test will follow the 8-hour SVE test on the second <br />through fourth days, with vapor and groundwater water dissolved oxygen (DO) sampling, air flow rates <br />in SVE/AS wells, and water levels and vacuum measurements in select monitoring wells taken at <br />startup and then once per 24-hour period. The pilot study results will be presented in a report with a <br />remediation recommendation for either a full scale SVE/AS system, or if conditions are unfavorable for <br />SVE/AS, a groundwater pump and treatment system. <br />Comments <br />The Workplan is approved with the following conditions. <br />1) The single completion monitoring well MW-7 screened interval shall be placed at a depth so <br />that the top of the well screen will not be submerged (depth to water at MW-4 was 11.32 feet in <br />October 2007) based on historic water levels for MW-4 and field conditions as determined by <br />the geologist. <br />California Environmental Protection Agency <br />Zc-ci Recycled Poper